1. Field of the Invention
The present invention relates to an optical communication device, and more particularly to a cycloolefin copolymeric (COC) optical communication device.
2. Description of the Related Art
As optical communication industry has progressed keen competition has arisen between companies. The selection of appropriate materials for device and module design has become a critical factor. Every potential material, for example has advantages and disadvantages. The conventional material, glass, has superior optical properties, but is brittle and as such is gradually being replaced by polymeric material. Polymeric materials have high impact strength and are easily molded by injection or extrusion molding, facilitate mass production, and offer reduced cost.
Polymeric materials applicable for optical communication devices feature the important properties of high transparency, low birefringence, low dispersion, high dimensional stability, superior mechanical properties, heat-resistance, and durability. Polymethylmethacrylate (PMMA), Polycarbonate (PC), and CR-39 resin are widely used as some commercial optical polymers have their respective advantages and disadvantages. PMMA has high transparency, low birefringence and is easily molded, but has poor heat and water resistance. PC has high transparency, high impact strength, and good heat resistance and is easily molded, but has high birefringence. CR-39 resin (mainly comprising diethylene glycol diallyl carbonate) is a thermal-setting resin able to bear temperatures greater than 100° C. after hardening. CR-39 has excellent hardness, and is suitable for grinding but not injection molding.
To meet the stringent requirements for optical communication devices, much effort has been made to develop a new-generation of polymeric materials, one such material is cycloolefin copolymer (COC). Typical COC materials are, for example, APEL (Mitsui Chemicals, Inc.), ARTON (JSR, Japan) and ZEONEX (Zeon, Japan).
Compared to other optical polymers such as PMMA, PC, or PS, COC is characterized by simplicity of material composition (mainly ethylene, mono-olefin, or poly-olefin), high-transparency, low water-absorption, and excellent physical and mechanical properties.
Though COC has great potential in the optical communication field, it is not yet widely applied. U.S. Pat. No. 5,637,400 discloses its application in an optical waveguide to ensure low transmission loss, but the waveguide is limited to an optical fiber.
Selection of materials for optical communication device is critical as unsuitable materials may have serious defects such as creating incompatible interfaces and the resulting signal-loss during transmission. For example, an incompatible interface may result between a core section and a cladding layer of a waveguide if they are made of different materials. The use of an appropriate material thus becomes critical in the manufacturing of an optical communication device.